I had this lens as my first standard upgrade lens in about 2006. I got some lovely photos but god its soft and distortion is redic. I ended up selling it and getting the 17-55mm missed the reach but the IQ was staggering in comparison.

From what I've read, there's substantial variation between copies of this lens. Some early copies had a lot of slop (to such an extent that the zoom position changes under its own weight). Those copies are apparently a lot softer than good copies.

On good copies, the softness and vignetting are both most obvious when the aperture is wide open at the 17mm end (see the St. Peter's photo for a great example of vignetting). For me, it's not bad enough to give up the extra reach without having to change lenses. YMMV.